Implement get_expiring_grants() for proactive grant lifecycle management

[Soushi888]

Overview

Implement a function to query capability grants that are expiring within a specified timeframe, enabling proactive grant lifecycle management.

Background

The capability-based sharing system (#27) sets expiration timestamps on grants but provides no mechanism to query upcoming expirations. Users and governance processes need to proactively manage expiring grants.

Implementation

Add get_expiring_grants(threshold_seconds: u64) to capability_based_sharing.rs:

• Query all grants via AgentToCapabilityMetadata links
• Filter for grants expiring within the threshold
• Return sorted by expiration time (soonest first)

Files

• dnas/nondominium/zomes/coordinator/zome_person/src/capability_based_sharing.rs
• tests/src/nondominium/person/person-capability-based-sharing.test.ts

Acceptance Criteria

• get_expiring_grants() function implemented and exposed as hdk_extern
• Returns grants expiring within the specified threshold
• Test coverage for expiring grant detection
• Handles edge cases: no grants, all expired, none expiring soon

Related

• Completed in Implement Enhanced Private Data Sharing System #27: Core capability-based sharing system